right click on taskbar>properties>start menu>customize
you have to have "display as a menu" selected for it to work.
They work for the options on the right hand column of the start menu only.
The "all program" on the left is hoverable, but only brings you down 1 level, show you all the program. If you have the shortcut in a folder, that won't open with hover and you have to click on it. At least that is for me as well. I never see that as a problem. I think this is just how window 7 is by design, can someone verify this?